create 3.x branch keeping Maven 3 XML parser implementation

pom.xml

@@ -26,16 +26,16 @@ limitations under the License.
   </parent>
 
   <artifactId>plexus-xml</artifactId>
-  <version>4.0.0-SNAPSHOT</version>
+  <version>3.0.0-SNAPSHOT</version>
 
   <name>Plexus XML Utilities</name>
-  <description>A collection of various utility classes to ease working with XML.</description>
+  <description>A collection of various utility classes to ease working with XML in Maven 3.</description>
 
   <scm>
     <connection>scm:git:git@github.com:codehaus-plexus/plexus-xml.git</connection>
     <developerConnection>scm:git:git@github.com:codehaus-plexus/plexus-xml.git</developerConnection>
     <url>http://github.com/codehaus-plexus/plexus-xml</url>
-    <tag>master</tag>
+    <tag>3.x</tag>
   </scm>
   <issueManagement>
     <system>github</system>
@@ -56,7 +56,7 @@ limitations under the License.
     <dependency>
       <groupId>org.codehaus.plexus</groupId>
       <artifactId>plexus-utils</artifactId>
-      <version>4.0.0-SNAPSHOT</version>
+      <version>4.0.0</version>
       <scope>test</scope>
     </dependency>
     <dependency>